iBatis習(xí)慣用的16條SQL語句

更新時(shí)間：2016年10月26日 16:52:31 作者：huiy_寧靜而致遠(yuǎn)

iBatis 是apache 的一個開源項(xiàng)目，一個O/R Mapping 解決方案，iBatis 最大的特點(diǎn)就是小巧，上手很快.這篇文章主要介紹了iBatis習(xí)慣用的16條SQL語句的相關(guān)資料,需要的朋友可以參考下

iBatis 簡介：

iBatis 是apache 的一個開源項(xiàng)目，一個O/R Mapping 解決方案，iBatis 最大的特點(diǎn)就是小巧，上手很快。如果不需要太多復(fù)雜的功能，iBatis 是能夠滿足你的要求又足夠靈活的最簡單的解決方案，現(xiàn)在的iBatis 已經(jīng)改名為Mybatis 了。

官網(wǎng)為：http://www.mybatis.org/

1.輸入?yún)?shù)為單個值

<delete id="com.fashionfree.stat.accesslog.deleteMemberAccessLogsBefore" 
parameterClass="long"> 
delete from 
MemberAccessLog 
where 
accessTimestamp = #value# 
</delete> 
<delete id="com.fashionfree.stat.accesslog.deleteMemberAccessLogsBefore" 
parameterClass="long"> 
delete from 
MemberAccessLog 
where 
accessTimestamp = #value# 
</delete>

2.輸入?yún)?shù)為一個對象

<insert id="com.fashionfree.stat.accesslog.MemberAccessLog.insert" 
parameterClass="com.fashionfree.stat.accesslog.model.MemberAccessLog> 
insert into MemberAccessLog 
( 
accessLogId, memberId, clientIP, 
httpMethod, actionId, requestURL, 
accessTimestamp, extend1, extend2, 
extend3 
) 
values 
( 
#accessLogId#, #memberId#, 
#clientIP#, #httpMethod#, 
#actionId#, #requestURL#, 
#accessTimestamp#, #extend1#, 
#extend2#, #extend3# 
) 
</insert> 
<insert id="com.fashionfree.stat.accesslog.MemberAccessLog.insert" 
parameterClass="com.fashionfree.stat.accesslog.model.MemberAccessLog> 
insert into MemberAccessLog 
( 
accessLogId, memberId, clientIP, 
httpMethod, actionId, requestURL, 
accessTimestamp, extend1, extend2, 
extend3 
) 
values 
( 
#accessLogId#, #memberId#, 
#clientIP#, #httpMethod#, 
#actionId#, #requestURL#, 
#accessTimestamp#, #extend1#, 
#extend2#, #extend3# 
) 
</insert>

3.輸入?yún)?shù)為一個java.util.HashMap

<select id="com.fashionfree.stat.accesslog.selectActionIdAndActionNumber" 
parameterClass="hashMap" 
resultMap="getActionIdAndActionNumber"> 
select 
actionId, count(*) as count 
from 
MemberAccessLog 
where 
memberId = #memberId# 
and accessTimestamp &gt; #start# 
and accessTimestamp &lt;= #end# 
group by actionId 
</select>
<select id="com.fashionfree.stat.accesslog.selectActionIdAndActionNumber" 
parameterClass="hashMap" 
resultMap="getActionIdAndActionNumber"> 
select 
actionId, count(*) as count 
from 
MemberAccessLog 
where 
memberId = #memberId# 
and accessTimestamp &gt; #start# 
and accessTimestamp &lt;= #end# 
group by actionId 
</select>

4.輸入?yún)?shù)中含有數(shù)組

<insert id="updateStatusBatch" parameterClass="hashMap"> 
update 
Question 
set 
status = #status# 
<dynamic prepend="where questionId in"> 
<isNotNull property="actionIds"> 
<iterate property="actionIds" open="(" close=")" conjunction=","> 
#actionIds[]# 
</iterate> 
</isNotNull> 
</dynamic> 
</insert> 
<insert id="updateStatusBatch" parameterClass="hashMap"> 
update 
Question 
set 
status = #status# 
<dynamic prepend="where questionId in"> 
<isNotNull property="actionIds"> 
<iterate property="actionIds" open="(" close=")" conjunction=","> 
#actionIds[]# 
</iterate> 
</isNotNull> 
</dynamic> 
</insert>

說明：actionIds為傳入的數(shù)組的名字；使用dynamic標(biāo)簽避免數(shù)組為空時(shí)導(dǎo)致sql語句語法出錯；使用isNotNull標(biāo)簽避免數(shù)組為null時(shí)ibatis解析出錯

5.傳遞參數(shù)只含有一個數(shù)組

<select id="com.fashionfree.stat.accesslog.model.StatMemberAction.selectActionIdsOfModule" 
resultClass="hashMap"> 
select 
moduleId, actionId 
from 
StatMemberAction 
<dynamic prepend="where moduleId in"> 
<iterate open="(" close=")" conjunction=","> 
#[]# 
</iterate> 
</dynamic> 
order by 
moduleId 
</select>
<select id="com.fashionfree.stat.accesslog.model.StatMemberAction.selectActionIdsOfModule" 
resultClass="hashMap"> 
select 
moduleId, actionId 
from 
StatMemberAction 
<dynamic prepend="where moduleId in"> 
<iterate open="(" close=")" conjunction=","> 
#[]# 
</iterate> 
</dynamic> 
order by 
moduleId 
</select>

說明：注意select的標(biāo)簽中沒有parameterClass一項(xiàng)

另：這里也可以把數(shù)組放進(jìn)一個hashMap中，但增加額外開銷，不建議使用

6.讓ibatis把參數(shù)直接解析成字符串

<select id="com.fashionfree.stat.accesslog.selectSumDistinctCountOfAccessMemberNum" 
parameterClass="hashMap" resultClass="int"> 
select 
count(distinct memberId) 
from 
MemberAccessLog 
where 
accessTimestamp &gt;= #start# 
and accessTimestamp &lt; #end# 
and actionId in $actionIdString$ 
</select> 
<select id="com.fashionfree.stat.accesslog.selectSumDistinctCountOfAccessMemberNum" 
parameterClass="hashMap" resultClass="int"> 
select 
count(distinct memberId) 
from 
MemberAccessLog 
where 
accessTimestamp &gt;= #start# 
and accessTimestamp &lt; #end# 
and actionId in $actionIdString$ 
</select>

說明：使用這種方法存在sql注入的風(fēng)險(xiǎn)，不推薦使用

7.分頁查詢 (pagedQuery)

<select id="com.fashionfree.stat.accesslog.selectMemberAccessLogBy" 
parameterClass="hashMap" resultMap="MemberAccessLogMap"> 
<include refid="selectAllSql"/> 
<include refid="whereSql"/> 
<include refid="pageSql"/> 
</select> 
<select id="com.fashionfree.stat.accesslog.selectMemberAccessLogBy.Count" 
parameterClass="hashMap" resultClass="int"> 
<include refid="countSql"/> 
<include refid="whereSql"/> 
</select> 
<sql id="selectAllSql"> 
select 
accessLogId, memberId, clientIP, 
httpMethod, actionId, requestURL, 
accessTimestamp, extend1, extend2, 
extend3 
from 
MemberAccessLog 
</sql> 
<sql id="whereSql"> 
accessTimestamp &lt;= #accessTimestamp# 
</sql> 
<sql id="countSql"> 
select 
count(*) 
from 
MemberAccessLog 
</sql> 
<sql id="pageSql"> 
<dynamic> 
<isNotNull property="startIndex"> 
<isNotNull property="pageSize"> 
limit #startIndex# , #pageSize# 
</isNotNull> 
</isNotNull> 
</dynamic> 
</sql>
<select id="com.fashionfree.stat.accesslog.selectMemberAccessLogBy" 
parameterClass="hashMap" resultMap="MemberAccessLogMap"> 
<include refid="selectAllSql"/> 
<include refid="whereSql"/> 
<include refid="pageSql"/> 
</select> 
<select id="com.fashionfree.stat.accesslog.selectMemberAccessLogBy.Count" 
parameterClass="hashMap" resultClass="int"> 
<include refid="countSql"/> 
<include refid="whereSql"/> 
</select> 
<sql id="selectAllSql"> 
select 
accessLogId, memberId, clientIP, 
httpMethod, actionId, requestURL, 
accessTimestamp, extend1, extend2, 
extend3 
from 
MemberAccessLog 
</sql> 
<sql id="whereSql"> 
accessTimestamp &lt;= #accessTimestamp# 
</sql> 
<sql id="countSql"> 
select 
count(*) 
from 
MemberAccessLog 
</sql> 
<sql id="pageSql"> 
<dynamic> 
<isNotNull property="startIndex"> 
<isNotNull property="pageSize"> 
limit #startIndex# , #pageSize# 
</isNotNull> 
</isNotNull> 
</dynamic> 
</sql>

說明：本例中，代碼應(yīng)為：

HashMap hashMap = new HashMap(); 
hashMap.put(“accessTimestamp”, someValue); 
pagedQuery(“com.fashionfree.stat.accesslog.selectMemberAccessLogBy”, hashMap);

pagedQuery方法首先去查找名為com.fashionfree.stat.accesslog.selectMemberAccessLogBy.Count 的mapped statement來進(jìn)行sql查詢，從而得到com.fashionfree.stat.accesslog.selectMemberAccessLogBy查詢的記錄個數(shù)，再進(jìn)行所需的paged sql查詢(com.fashionfree.stat.accesslog.selectMemberAccessLogBy)，具體過程參見utils類中的相關(guān)代碼

8.sql語句中含有大于號>、小于號< 1. 將大于號、小于號寫為： > < 如：

<delete id="com.fashionfree.stat.accesslog.deleteMemberAccessLogsBefore" parameterClass="long"> 
delete from 
MemberAccessLog 
where 
accessTimestamp &lt;= #value# 
</delete> 
Xml代碼 
<delete id="com.fashionfree.stat.accesslog.deleteMemberAccessLogsBefore" parameterClass="long"> 
delete from 
MemberAccessLog 
where 
accessTimestamp &lt;= #value# 
</delete>

將特殊字符放在xml的CDATA區(qū)內(nèi)：

<delete id="com.fashionfree.stat.accesslog.deleteMemberAccessLogsBefore" parameterClass="long"> 
<![CDATA[ 
delete from 
MemberAccessLog 
where 
accessTimestamp <= #value# 
]]> 
</delete> 
<delete id="com.fashionfree.stat.accesslog.deleteMemberAccessLogsBefore" parameterClass="long"> 
<![CDATA[ 
delete from 
MemberAccessLog 
where 
accessTimestamp <= #value# 
]]> 
</delete>

推薦使用第一種方式，寫為< 和 > (XML不對CDATA里的內(nèi)容進(jìn)行解析，因此如果CDATA中含有dynamic標(biāo)簽，將不起作用)

9.include和sql標(biāo)簽將常用的sql語句整理在一起，便于共用：

<sql id="selectBasicSql"> 
select 
samplingTimestamp,onlineNum,year, 
month,week,day,hour 
from 
OnlineMemberNum 
</sql> 
<sql id="whereSqlBefore"> 
where samplingTimestamp &lt;= #samplingTimestamp# 
</sql> 
<select id="com.fashionfree.accesslog.selectOnlineMemberNumsBeforeSamplingTimestamp" parameterClass="hashmap" resultClass="OnlineMemberNum"> 
<include refid="selectBasicSql" /> 
<include refid="whereSqlBefore" /> 
</select> 
<sql id="selectBasicSql"> 
select 
samplingTimestamp,onlineNum,year, 
month,week,day,hour 
from 
OnlineMemberNum 
</sql> 
<sql id="whereSqlBefore"> 
where samplingTimestamp &lt;= #samplingTimestamp# 
</sql> 
<select id="com.fashionfree.accesslog.selectOnlineMemberNumsBeforeSamplingTimestamp" parameterClass="hashmap" resultClass="OnlineMemberNum"> 
<include refid="selectBasicSql" /> 
<include refid="whereSqlBefore" /> 
</select>

注意：sql標(biāo)簽只能用于被引用，不能當(dāng)作mapped statement。如上例中有名為selectBasicSql的sql元素，試圖使用其作為sql語句執(zhí)行是錯誤的:

sqlMapClient.queryForList(“selectBasicSql”); ×

10.隨機(jī)選取記錄

<sql id=”randomSql”> 
ORDER BY rand() LIMIT #number# 
</sql>

從數(shù)據(jù)庫中隨機(jī)選取number條記錄（只適用于MySQL）

11.將SQL GROUP BY分組中的字段拼接

<sql id=”selectGroupBy> 
SELECT 
a.answererCategoryId, a.answererId, a.answererName, 
a.questionCategoryId, a.score, a.answeredNum, 
a.correctNum, a.answerSeconds, a.createdTimestamp, 
a.lastQuestionApprovedTimestamp, a.lastModified, GROUP_CONCAT(q.categoryName) as categoryName 
FROM 
AnswererCategory a, QuestionCategory q 
WHERE a.questionCategoryId = q.questionCategoryId 
GROUP BY a.answererId 
ORDER BY a.answererCategoryId 
</sql>
<sql id=”selectGroupBy> 
SELECT 
a.answererCategoryId, a.answererId, a.answererName, 
a.questionCategoryId, a.score, a.answeredNum, 
a.correctNum, a.answerSeconds, a.createdTimestamp, 
a.lastQuestionApprovedTimestamp, a.lastModified, GROUP_CONCAT(q.categoryName) as categoryName 
FROM 
AnswererCategory a, QuestionCategory q 
WHERE a.questionCategoryId = q.questionCategoryId 
GROUP BY a.answererId 
ORDER BY a.answererCategoryId 
</sql>

注：SQL中使用了MySQL的GROUP_CONCAT函數(shù)

12.按照IN里面的順序進(jìn)行排序

①M(fèi)ySQL:

<sql id=”groupByInArea”> 
select 
moduleId, moduleName, 
status, lastModifierId, lastModifiedName, 
lastModified 
from 
StatModule 
where 
moduleId in (3, 5, 1) 
order by 
instr(',3,5,1,' , ','+ltrim(moduleId)+',') 
</sql> 
<sql id=”groupByInArea”> 
select 
moduleId, moduleName, 
status, lastModifierId, lastModifiedName, 
lastModified 
from 
StatModule 
where 
moduleId in (3, 5, 1) 
order by 
instr(',3,5,1,' , ','+ltrim(moduleId)+',') 
</sql>

②SQLSERVER:

<sql id=”groupByInArea”> 
select 
moduleId, moduleName, 
status, lastModifierId, lastModifiedName, 
lastModified 
from 
StatModule 
where 
moduleId in (3, 5, 1) 
order by 
charindex(','+ltrim(moduleId)+',' , ',3,5,1,') 
</sql> 
<sql id=”groupByInArea”> 
select 
moduleId, moduleName, 
status, lastModifierId, lastModifiedName, 
lastModified 
from 
StatModule 
where 
moduleId in (3, 5, 1) 
order by 
charindex(','+ltrim(moduleId)+',' , ',3,5,1,') 
</sql>

說明：查詢結(jié)果將按照moduleId在in列表中的順序(3, 5, 1)來返回

MySQL : instr(str, substr)

SQLSERVER: charindex(substr, str) 返回字符串str 中子字符串的第一個出現(xiàn)位置 ltrim(str) 返回字符串str, 其引導(dǎo)(左面的)空格字符被刪除

13.resultMap resultMap負(fù)責(zé)將SQL查詢結(jié)果集的列值映射成Java Bean的屬性值

<resultMap class="java.util.HashMap" id="getActionIdAndActionNumber"> 
<result column="actionId" property="actionId" jdbcType="BIGINT" javaType="long"/> 
<result column="count" property="count" jdbcType="INT" javaType="int"/> 
</resultMap> 
Xml代碼 
<resultMap class="java.util.HashMap" id="getActionIdAndActionNumber"> 
<result column="actionId" property="actionId" jdbcType="BIGINT" javaType="long"/> 
<result column="count" property="count" jdbcType="INT" javaType="int"/> 
</resultMap>

使用resultMap稱為顯式結(jié)果映射，與之對應(yīng)的是resultClass(內(nèi)聯(lián)結(jié)果映射)，使用resultClass的最大好處便是簡單、方便，不需顯示指定結(jié)果，由iBATIS根據(jù)反射來確定自行決定。而resultMap則可以通過指定jdbcType和javaType，提供更嚴(yán)格的配置認(rèn)證。

14.typeAlias

<typeAlias alias="MemberOnlineDuration" type="com.fashionfree.stat.accesslog.model.MemberOnlineDuration" /> 
<typeAlias>

允許你定義別名，避免重復(fù)輸入過長的名字

15.remap

<select id="testForRemap" parameterClass="hashMap" resultClass="hashMap" remapResults="true"> 
select 
userId 
<isEqual property="tag" compareValue="1"> 
, userName 
</isEqual> 
<isEqual property="tag" compareValue="2"> 
, userPassword 
</isEqual> 
from 
UserInfo 
</select> 
<select id="testForRemap" parameterClass="hashMap" resultClass="hashMap" remapResults="true"> 
select 
userId 
<isEqual property="tag" compareValue="1"> 
, userName 
</isEqual> 
<isEqual property="tag" compareValue="2"> 
, userPassword 
</isEqual> 
from 
UserInfo 
</select>

此例中，根據(jù)參數(shù)tag值的不同，會獲得不同的結(jié)果集，如果沒有remapResults="true"屬性，iBatis會將第一次查詢時(shí)的結(jié)果集緩存，下次再執(zhí)行時(shí)（必須還是該進(jìn)程中）不會再執(zhí)行結(jié)果集映射，而是會使用緩存的結(jié)果集。

因此，如果上面的例子中remapResult為默認(rèn)的false屬性，而有一段程序這樣書寫：

HashMap<String, Integer> hashMap = new HashMap<String, Integer>(); 
hashMap.put("tag", 1); 
sqlClient.queryForList("testForRemap", hashMap); 
hashMap.put("tag", 2); 
sqlClient.queryForList("testForRemap", hashMap);

Java代碼

HashMap<String, Integer> hashMap = new HashMap<String, Integer>(); 
hashMap.put("tag", 1); 
sqlClient.queryForList("testForRemap", hashMap); 
hashMap.put("tag", 2); 
sqlClient.queryForList("testForRemap", hashMap);

則程序會在執(zhí)行最后一句的query查詢時(shí)報(bào)錯，原因就是iBATIS使用了第一次查詢時(shí)的結(jié)果集，而前后兩次的結(jié)果集是不同的:(userId, userName)和(userId, userPassword)，所以導(dǎo)致出錯。如果使用了remapResults="true"這一屬性，iBATIS會在每次執(zhí)行查詢時(shí)都執(zhí)行結(jié)果集映射，從而避免錯誤的發(fā)生（此時(shí)會有較大的開銷）。

16.dynamic標(biāo)簽的prepend dynamic標(biāo)簽的prepend屬性作為前綴添加到結(jié)果內(nèi)容前面，當(dāng)標(biāo)簽的結(jié)果內(nèi)容為空時(shí)，prepend屬性將不起作用。

當(dāng)dynamic標(biāo)簽中存在prepend屬性時(shí)，將會把其嵌套子標(biāo)簽的第一個prepend屬性忽略。例如：

<sql id="whereSql"> 
<dynamic prepend="where "> 
<isNotNull property="userId" prepend="BOGUS"> 
userId = #userId# 
</isNotNull> 
<isNotEmpty property="userName" prepend="and "> 
userName = #userName# 
</isNotEmpty> 
</dynamic> 
</sql> 
<sql id="whereSql"> 
<dynamic prepend="where "> 
<isNotNull property="userId" prepend="BOGUS"> 
userId = #userId# 
</isNotNull> 
<isNotEmpty property="userName" prepend="and "> 
userName = #userName# 
</isNotEmpty> 
</dynamic> 
</sql>

此例中，dynamic標(biāo)簽中含有兩個子標(biāo)簽<isNotNull>和<isNotEmpty>。根據(jù)前面敘述的原則，如果<isNotNull>標(biāo)簽中沒有prepend="BOGUS" 這一假的屬性來讓dynamic去掉的話，<isNotEmpty>標(biāo)簽中的and就會被忽略，會造成sql語法錯誤。

注意：當(dāng)dynamic標(biāo)簽沒有prepend屬性時(shí)，不會自動忽略其子標(biāo)簽的第一個prepend屬性。

以上所述是小編給大家介紹的iBatis習(xí)慣用的16條SQL語句，希望對大家有所幫助，如果大家有任何疑問請給我留言，小編會及時(shí)回復(fù)大家的。在此也非常感謝大家對腳本之家網(wǎng)站的支持！

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